456  
FXCA20 KWBC 281924  
PMDCA  
 
TROPICAL DISCUSSION - INTERNATIONAL DESKS  
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD  
224 PM EST TUE NOV 28 2017  
 
TROPICAL DISCUSSION FROM NOV 28/12 UTC: WEST OVER THE DOMAIN...AT  
500 HPA...A HIGH OVER SOUTHWEST MEXICO ANCHORS A SHORT WAVE RIDGE  
ACROSS THE CENTRAL/NORTHERN STATES OF MEXICO. THIS RIDGE IS  
FORECAST TO HOLD DURING THE NEXT FEW DAYS. MEANWHILE...IT IS TO  
SUSTAIN A CAP INVERSION THAT IS TO INHIBIT ORGANIZED DEEP  
CONVECTION. AT LOW LEVELS...A HIGH OVER SOUTHERN  
TEXAS/NORTHEASTERN MEXICO ON WEDNESDAY IS TO FAVOR A NORTHEASTERLY  
FLOW ACROSS THE GULF TO THE YUCATAN-SOUTHERN STATES OF  
MEXICO-WESTERN CARIBBEAN/NORTHERN HONDURAS. OVER NORTHERN  
CHIAPAS-SOUTHERN VERACRUZ THIS IS TO FAVOR RAINFALL AMOUNTS OF  
00-05MM/DAY AND MAXIMA OF 10MM/DAY ON WEDNESDAY-FRIDAY. ACROSS  
SOUTHERN BELIZE-NORTHERN HONDURAS THE NORTHERLIES ARE TO FAVOR  
MODERATE RAINFALL AMOUNTS ON WEDNESDAY-THURSDAY...WITH RAINFALL  
AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-35MM. ON FRIDAY...MOST  
ACTIVE IS EXPECTED OVER NORTHWEST HONDURAS/SOUTHERN BELIZE WITH  
ACCUMULATION OF 10-15MM/DAY AND MAXIMA OF 20-30MM. ACROSS  
NORTHEAST HONDURAS...MEANWHILE...IT WILL DECREASE TO 05-10MM/DAY  
AND MAXIMA OF 15-20MM.  
 
EAST OF THIS RIDGE...A MID/UPPER LEVEL LOW OVER THE EASTERN GULF  
ANCHORS A SHORT WAVE TROUGH THAT EXTENDS SOUTH TO THE CAMPECHE  
SOUND/YUCATAN PENINSULA. THE TROUGH IS TO LIFT OVER A MID/UPPER  
LEVEL RIDGE TO THE EAST...LIFTING ACROSS FLORIDA-THE BAHAMAS LATER  
ON WEDNESDAY. THIS IS TO THEN CONTINUE TO THE EAST-SOUTHEAST...  
REACHING NORTHERN HISPANIOLA ON THURSDAY AFTERNOON. AS IT MEANDERS  
OVER THE WESTERN ATLANTIC THIS IS TO INTERACT WITH A MEANDERING  
FRONT NORTH OF THE GREATER ANTILLES-BAHAMAS...INDUCING  
CYCLOGENESIS JUST NORTH OF GRAND BAHAMA ON WEDNESDAY...WITH THE  
LOW TO THEN MEANDER EAST ACROSS THE ATLANTIC MOVING TO THE NORTH  
OF PUERTO RICO ON THURSDAY. AS IT INTERACTS WITH THE FRONT OVER  
THE BAHAMAS...INITIALLY EXPECTING RAINFALL AMOUNTS OF 15-20MM/DAY  
AND MAXIMA OF 35-70MM...WHILE ACROSS CUBA EXPECTING ACCUMULATION  
OF 10-15MM/DAY AND MAXIMA OF 20-35MM. ON WEDNESDAY...OVER THE  
NORTHWEST-CENTRAL BAHAMAS AND WESTERN CUBA EXPECTING RAINFALL  
AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM...WHILE OVER THE  
TURKS/SOUTHEAST BAHAMAS-EASTERN CUBA EXPECTING ACCUMULATION OF  
05-10MM/DAY AND MAXIMA OF 15-20MM. THROUGH WEDNESDAY-THURSDAY IT  
DECREASES TO 00-05MM/DAY AND MAXIMA OF 10MM.  
 
ALSO AT LOW LEVELS...A DEEP LAYER EASTERLY FLOW DOMINATES THE  
EASTERN-CENTRAL CARIBBEAN...WITH FLOW CONVERGING ALONG A  
SOUTHEAST-TO-NORTHWEST TROUGH OVER THE CENTRAL CARIBBEAN. THE  
TROUGH EXTENDS FROM COSTA RICA/WESTERN PANAMA TO JUST WEST OF THE  
CAYMAN ISLES. THE LOW LEVEL PERTURBATION IS FORECAST TO DISSIPATE  
LATER ON WEDNESDAY. MEANWHILE...THIS IS TO ENHANCE CONVECTION  
ACROSS SAN ANDRES ISLAND-ISLA DE PROVIDENCIA/EASTERN  
NICARAGUA...WHERE IT IS TO FAVOR RAINFALL AMOUNTS OF 10-15MM/DAY  
AND MAXIMA OF 20-30MM. ON WEDNESDAY MOST ACTIVE IS EXPECTED ACROSS  
SOUTHERN NICARAGUA...WITH MAXIMA OF 20-40MM. THROUGH  
THURSDAY-FRIDAY THIS DECREASES TO 05-10MM/DAY AND MAXIMA OF  
15-20MM. OTHER CONVECTION TO THE NORTH IS EXPECTED OVER THE CAYMAN  
ISLES AND JAMAICA. OVER THE CAYMAN ISLANDS THIS IS TO SUSTAIN  
RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF 15MM. ACROSS JAMAICA  
THIS IS TO TRIGGER RAINFALL AMOUNTS OF 05-10MM/DAY AND MAXIMA OF  
15-30MM/DAY. AS THE TROUGH WEAKENS ON WEDNESDAY...ACTIVITY TO THE  
NORTHWEST WILL WANE. OVER JAMAICA THIS GRADUALLY DECREASES TO  
00-05MM/DAY AND ISOLATED MAXIMA OF 10MM...WHILE OVER THE CAYMAN  
THE MAXIMA ON WEDNESDAY PEAKS AT 15MM.  
 
OVER PANAMA-COSTA RICA ITCZ RELATED CONVERGENCE IS TO TRIGGER  
RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-30MM. ON  
WEDNESDAY...AS A NORTHEASTERLY WIND SURGE ENVELOPS THE  
ISTHMUS...THIS INCREASES TO 10-15MM/DAY AND MAXIMA OF 20-40MM. ON  
THURSDAY-FRIDAY IT...HOWEVER...DECREASES TO 05-10MM/DAY AND MAXIMA  
OF 15-20MM. OVER COLOMBIA...AN ILL ORGANIZED CELL OF THE  
PANAMANIAN LOW/TROUGH FAVORS A MOIST WESTERLY FLOW THAT IS  
CONVERGING ALONG THE WESTERN PLAINS. IN THIS AREA INITIALLY  
EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-40MM.  
ON WEDNESDAY-FRIDAY THIS INCREASES TO 15-20MM/DAY AND MAXIMA OF  
25-50MM. ON THE ANDEAN REGION-EASTERN PLAINS OF  
COLOMBIA...MEANWHILE...EXPECTING RAINFALL AMOUNTS OF 05-10MM/DAY  
AND MAXIMA OF 15MM. OVER SOUTHERN VENEZUELA MOST ACTIVE IS  
EXPECTED ACROSS AMAZONIA TO THE SOUTH. EARLY IN THE CYCLE  
EXPECTING RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-30MM.  
ON WEDNESDAY AND ONWARD IT DECREASES TO 05-10MM/DAY AND MAXIMA OF  
15-20MM.  
 
BROAD CELL OF THE SUBEQUATORIAL RIDGE TO THE EAST DOMINATES THE  
MID/UPPER LEVEL FLOW ACROSS THE CENTRAL/EASTERN CARIBBEAN-NORTHERN  
SOUTH AMERICA INTO THE WESTERN ATLANTIC. AT 500 HPA THE MID LEVEL  
RIDGE ANCHORS ON A CLOSED HIGH TO THE EAST-NORTHEAST OF ANTIGUA.  
UNDER PRESSURE FROM THE AFOREMENTIONED TROUGH OVER THE  
BAHAMAS-WESTERN ATLANTIC...THE CARIBBEAN RIDGE IS TO FLATTEN EARLY  
IN THE CYCLE...TO THEN CONFINE TO AREA SOUTH OF 20N. THE MID LEVEL  
RIDGE SUSTAINS A SUBSIDENCE CAP ACROSS THE LESSER ANTILLES-VIRGIN  
ISLES-PUERTO RICO. ALTHOUGH THE CAP TENDS TO HOLD OVER THE ISLAND  
CHAIN DURING THE NEXT FEW DAYS...OVER THE NORTHERN LEEWARD/VIRGIN  
ISLES-PUERTO RICO IT BRIEFLY RELAXES ITS FOOTHOLD ON WEDNESDAY.  
HOWEVER...IN THE ABSENCE OF MESO/SYNOPTIC FORCING ONLY EXPECTING  
LIGHT RAINFALL AMOUNTS ON WEDNESDAY-THURSDAY...WITH RAINFALL  
AMOUNTS OF 00-05MM/DAY AND MAXIMA OF 10MM. LIGHT CONVECTION  
SPREADS TO THE DOMINICAN REPUBLIC ON WEDNESDAY-THURSDAY...TO  
TRIGGER RAINFALL AMOUNTS OF 00-05MM/DAY AND MAXIMA OF 10MM.  
 
TROPICAL/EASTERLY WAVES INITIALIZED AT 12UTC:  
INITIAL 24 36 48 60 72 84 96 TYPE  
SOF  
51W 54W 57W 59W 61W 64W 67W 69W TUTT-INDCD  
12N  
66W 69W 71W 73W 74W DISSIPATES TUTT-INDCD  
24N  
 
A TUTT INDUCED EASTERLY WAVE IS INITIALIZED ALONG 51W AND TO THE  
SOUTH OF 12N. ACROSS NORTHERN FRENCH GUIANA-SURINAME THIS IS TO  
FAVOR RAINFALL AMOUNTS OF 00-05MM/DAY AND MAXIMA OF 10MM. HIGHER  
AMOUNTS ARE EXPECTED OVER NORTHERN GUIANA-ORINOCO DELTA REGION AND  
TRINIDAD AND TOBAGO...WHERE IN INTERACTION WITH THE ITCZ THIS IS  
TO SUSTAIN RAINFALL AMOUNTS OF 10-15MM/DAY AND MAXIMA OF 20-45MM  
ON WEDNESDAY. ON THURSDAY THE DAILY MAXIMA INCREASES TO  
25-50MM...WHILE ON FRIDAY IT IS TO PEAK AT 20-40MM. ACROSS  
NORTHEAST VENEZUELA THIS IS TO FAVOR ADDITIONAL RAINFALL AMOUNTS  
OF 05-10MM/DAY AND MAXIMA OF 15-20MM ON THURSDAY. SIMILARLY OVER  
AMAZONIA TO THE SOUTH.  
 
A TUTT INDUCED WAVE ALONG 66W AND TO THE NORTH OF 16N...SUSTAINS A  
CYCLONIC CIRCULATION NORTH OF THE ISLANDS. THIS...HOWEVER...LIES  
ON THE CONVERGENT SIDE OF THE MID LEVEL ANTICYCLONE ENVELOPING THE  
EASTERN CARIBBEAN. AS THEY INTERACT...MOST ACTIVE CONVECTION WITH  
THIS WAVE IS TO FOLLOW SEVERAL HOURS LATER. PLUME OF SHALLOW  
TROPICAL MOISTURE IS TO THEN REACH PUERTO RICO EARLY ON WEDNESDAY  
MORNING...TO SUSTAIN RAINFALL AMOUNTS OF 00-05MM/DAY AND MAXIMA OF  
10MM. ACROSS HISPANIOLA THIS IS TO THEN TRIGGER RAINFALL AMOUNTS  
OF 00-05MM/DAY AND MAXIMA OF 10MM. THE WAVE THEN DISSIPATES ON  
THURSDAY.  
 
GUY...NMS (BELIZE)  
PECK...MS (JAMAICA)  
RIVAS...SENAMHI (PERU)  
DAVISON...WPC (USA)  
 

 
 
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